The present invention relates to rice-hulling rollers of the type including a cylindrical core or drum and a layer of abrasion-resistant elastomer or the like provided on the outer surface of the core.
A rice-hulling roller usually includes a core (or drum) comprising a metal cylinder and a boss section for supporting the cylinder on a machine, and an abrasion-resistant elastomer layer on the outer circumference of the cylindrical core. Such rice-hulling rollers may be roughly classified as follows:
A. Those having a rigid structure
(a) Having an integral core structure (casting, etc.); or PA1 (b) Having a core made of iron plate; PA1 (c) Having a core made of iron plate, with a resilient coupling between the cylinder and the boss section.
B. Those having a Flexible structure
Rice-hulling rollers of the foregoing character have the following disadvantages:
1. A roller having a core formed by a casting (construction a) is heavy and requires a large driving force, and the load is large.
2. Since a cast core is not formed accurately and its dynamic balance is not good, the machine will be adversely affected and will generate excessive vibration and noise. Further, such a roller is brittle and is vulnerable to cracking due to impact during handling, and also cracking due to intrusion of foreign matter during hulling operation.
3. On the other hand, castings made of aluminum may be lighter in weight and have good dynamic balance. The aluminum rollers, however, still have a rigid construction, and the machine is directly affected by an intrusion of a foreign matter, resulting in frequent maintenance of the machine.
4. A roller having a core made of iron plate (construction b) is made from plate which has formed by deep drawing, curling, and welding, and accordingly its formed accuracy is low, with insufficient circularity and excessive runout. Its dynamic balance, in turn, is poor and excessive vibration is generated. When a foreign matter is fed into the machine, the drum circumference tends to be deformed and not easily restored to its original shape.
5. In the case of a flexible roller (construction c), while the shock absorption is improved, buckling tends to occur in the resilient layer, resulting in excessive noise. Further, the resilient layer tends to be broken when an excessive load is applied to the roller, and the durability of the roller is inadequate.
It is a general object of the present invention to avoid the above-mentioned disadvantages and to provide a rice-hulling roller which does not vibrate and has an excellent durability whereby the core is unlikely to crack even if foreign matter is fed into the machine.